Many American teens engage in the habitual use of chewing or smokeless tobacco (ST) and wish to quit but lack resources. This project meets the goals of the National Cancer Institute for providing tobacco cessation services to underserved populations of users and the renewed focus on evaluation of new and innovative cessation programs for young people. Given that teens are heavy users of the Internet and there are promising signs that web-based interventions for other health behaviors have been helpful, we propose to develop and test the effectiveness of an Internet-based ST cessation program targeted to teens. This proposed two-arm randomized control trial will compare the efficacy of a targeted, tailored, and highly interactive ST cessation website to a control website that presents information that the moderately skillful Internet search user could locate. The core features of the intervention include: a) targeted to teen ST users;b) tailored content based on ongoing participant interaction with the program;c) personalized, dynamic presentation of ST cessation tools, maintenance resources, and information;and d) monitored online peer-to-peer and expert-to-participant ST cessation support in a web forum. Participants in the control condition will be exposed to a more static informational website containing ST cessation content, with annotated links to information-only ST resources on the Internet. A multifaceted plan-aimed both attendees and persons who could refer them-will be used to recruit 1,550 participants ages 14-18. The primary outcomes are tobacco cessation at 6 weeks and 7.5 months post-enrollment, with quit rates expected to be higher in teens enrolled in the tailored, targeted interactive condition. We will also investigate baseline subject characteristics, program engagement, and process variables as predictive of cessation outcomes: A cost analysis will determine the cost per quit and relative cost-effectiveness of the two conditions. The public health potential of the proposed Internet-based tobacco cessation program for teen ST users is great. Relevance: An empirical evaluation of an web delivered cessation program for this underserved teen audience of smokeless tobacco users is both warranted and timely. Given that a vast majority of adult tobacco users started their use before age 18, and there are few cessation resources available to teen tobacco users, there is great public health potential in using the Internet to assist young ST users in quitting early in their addiction process.